Wireless LAN systems are proposed that utilize Multiple Input Multiple Output (MIMO) transmission technology for high throughput extensions to the IEEE 802.11 standard by the IEEE 802.11n Task Group. MIMO techniques promise a significant throughput increase over legacy techniques, however, they consume more power for increased signal processing, and, for the same range, require transmitted power to be roughly N times that of a single channel, where N is the number of channels used to transmit a signal.
This problem may be alleviated using specific signaling mechanisms which use MIMO only when there is data that must be transmitted over multiple channels. Such signaling mechanisms, as currently exist in IEEE 802.11e, may be used to determine the number of channels that are used for a given transmission to instantiate MIMO processing. By using the Transmission Specification (TSPEC) reservation mechanism, in particular, MIMO processing may be used only when needed, thereby saving power. A thorough discussion and description of legacy IEEE 802.11 systems and MIMO may be found in IEEE 802.11e Draft 6.0, IEEE 802.11-1999 Std. 2003 Edition, and Gesbert et al., From Theory to Practice: An Overview of MIMO Space-Time Coded Wireless Systems, IEEE JSAC, Apr. 2003, pp. 281-302.
United States Patent Application No. 20030072283 Al of Varshney et al., published Apr. 17, 2003, for Method and system to increase QoS and range in a multicarrier system, describes a MIMO system with multiple coding layers for EDGE, etc.
United States Patent Application No. 20030072283 Al of Varshney et al., published Apr. 17, 2003, for Method and system to increase QoS and range in a multicarrier system, describes coding and multi-carrier techniques.
United States Patent Application No. 20030231715 Al of Shoemaker et al., published Dec. 18, 2003, for Methods for optimizing time variant communication channels, describes multi-channel modulation and signal processing.
United States Patent Application No. 20030185241 Al of Lu et al., published Oct. 2, 2003, for Wireless network scheduling data frames including physical layer configuration, describes a method of implementing communication frames in a wireless network having a plurality of wireless devices, some of which are capable of different physical layer configurations than other of the devices, which include (a) forming a polling frame including at least one bit in which physical layer configuration information is encoded, wherein the configuration information is capable of specifying whether a single input single output (SISO) antenna configuration is to be used or a multiple input multiple output (MIMO) antenna configuration is to be used; (b) transmitting the polling frame to a receiving device for decoding by the receiving device; and (c) configuring a physical layer of the receiving device in accordance with the physical layer configuration information contained in the polling frame; wherein the polling frame also causes the receiving device to determine whether it has information to return.
United States Patent Application No. 20030169769 Al of Ho et al., published Sep. 11, 2003, for MAC extensions for smart antenna support, describes an apparatus and method to implement aggregation frames and allocation frames.
WO 03/003672, of Dohler et al., published Jan. 9, 2003, for Improvements in or relating to electronic data communication system, describes a variant of a CDMA system.